Organic light emitting display apparatus

ABSTRACT

An apparatus includes a plurality of pixels on a substrate; a gate driver disposed outside of the plurality of pixels; a common voltage line disposed outside both of the gate driver and the plurality of pixels, the common voltage line having a first cross-sectional width; a dam structure configured to surround the plurality of pixels and disposed on at least a portion of the common voltage line, the dam structure having a second cross-sectional width narrower than the first cross-sectional width; a first inorganic encapsulation layer configured to cover the plurality of pixels, the gate driver, the common voltage line and the dam structure; a cover layer disposed on the first inorganic encapsulation layer and configured to be surrounded by the dam structure; and a second encapsulation layer disposed on the first encapsulation layer and the cover layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. patent applicationSer. No. 14/749,431 filed on Jun. 24, 2015, which claims the benefitunder 35 U.S.C. §119(a) to Korean Patent Application Nos.10-2015-0088088 filed on Jun. 22, 2015, 10-2014-0078748 filed on Jun.26, 2014, 10-2014-0078438 filed on Jun. 25, 2014 and 10-2014-0078252filed on Jun. 25, 2014, all of which are hereby expressly incorporatedby reference into the present application.

BACKGROUND OF THE INVENTION

Field of the Invention

The embodiments of the present disclosure relate to an organiclight-emitting display (OLED) device, and more particularly to an OLEDdevice capable of suppressing a particle cover layer from beingexcessively spread.

Discussion of the Related Art

As the era of information technology has unfolded, the field of displaydevices has been growing rapidly, as information can be represented inelectrical signals in the form of visual images. In accordance withthis, research is ongoing for various flat panel display devices to makethem thinner, lighter and capable of consuming less power. Flat paneldisplay devices include a liquid crystal display (LCD) device, a plasmadisplay panel (PDP) device, a field emission display (FED) device, anelectro-wetting display (EWD) device, and an organic light emittingdisplay (OLED) device, etc.

Among others, an OLED device is capable of producing light on its own,and thus, does not require an additional light source, unlike an LCD.Therefore, an OLED device can be made lighter and thinner. Further, anOLED device has advantages in that it is driven with low voltage toconsume less power, and it has fast response time, wide viewing angleand infinite contrast ratio (CR). For these reasons, an OLED device isacknowledged as the next generation display device. However, an OLEDdevice is especially vulnerable to moisture and oxygen permeation,making it is less reliable than other flat panel display devices.

An OLED device displays images using an organic light-emitting elementwhich is self-luminous. An OLED device includes a plurality of pixels,each of which includes an organic light-emitting element. An organiclight-emitting element includes a first electrode and second electrodefacing each other. The organic light-emitting element further includes alight-emitting layer disposed between the first electrode and the secondelectrode, and is made of an organic substance and createselectroluminescence.

For a top emission OLED device, a first electrode is transparent ortransflective (semi-transparent) while a second electrode is reflective,so that light generated from an organic light-emitting layer is emittedupwardly through the first electrode. Additionally, in order to ensurethe reliability of an OLED device, a transparent, encapsulation unit isformed on the organic light-emitting element to protect the organiclight-emitting element from oxygen and moisture. Previously in a topemission OLED device, a glass encapsulation unit was employed as theencapsulation unit.

SUMMARY OF THE INVENTION

Recently, as a replacement for inflexible flat panel display devices, aflexible organic light emitting display (FOLED) is under development. AFOLED employs a flexible substrate made of a flexible material such asplastic and can be bent like paper while still exhibiting its displayfunctionality.

In view of the above, the inventors of the embodiments of the presentdisclosure have been studying to commercialize FOLED devices. Meanwhile,the inventors of the embodiments of the present disclosure haveconcluded that a glass substrate is not appropriate for an encapsulationunit since it is not flexible. Accordingly, the inventors of theapplication have studied on a novel, transparent and flexibleencapsulation layer, which can be mass-produced and commerciallyavailable.

Specifically, there has been an attempt to implement an encapsulationunit of an FOLED device by using a single, flexible encapsulation layermade of an inorganic substance. However, such a flexible encapsulationlayer has poor flowability and is too thin to fully cover the foreignmatter, and thus, cracks are easily made by the foreign matter such asdust or particles. Therefore, moisture permeates through the cracks andcauses defects in the FOLED. As defects occur, production yield becomeslower, leading to a serious problem for implementing mass production.

Under the circumstances, the inventors have devised a flexibleencapsulation unit capable of improving the foreign matter-relatedissues, in such a manner that a particle cover layer made of an organicsubstance having good flowability is disposed on a flexibleencapsulation layer in order to cover the foreign matter by making thetop surface of the particle cover layer even, and then another singleflexible encapsulation layer made of an inorganic substance is disposedon the even surface of the particle cover layer.

With high flowability, the particle cover layer effectively covers theforeign matter. However, it is difficult to control the region where theparticle cover layer is applied to. That is, the organic substance ofthe particle cover layer easily flows in an unwanted direction. Inaddition, in order to make a narrow bezel, the area of the non-pixelbecomes smaller. It makes the control over the particle cover layer moredifficult. As a result, the particle cover layer is spread beyond theoriginally designed region. Hereinafter, this is referred to as an“excessive spread.” In case a particle cover layer is excessivelyspread, it can be perceived as a spot, spoiling the appearance of anFOLED. In addition, as the particle cover layer cannot effectivelyprotect moisture permeation, moisture may permeate through theexcessively spread area.

In conclusion, for a FOLED device including a flexible encapsulationunit in which a first encapsulation layer is disposed, a particle coverlayer is applied onto a part of the first encapsulation layer, and asecond encapsulation layer is disposed on the particle cover layer andthe first encapsulation layer, yet an excessive spread of the particlecover layer is one of the biggest issues that have to be overcome.

The inventors of the embodiments of the present disclosure have reachedthe idea that the excessive spread can be effectively suppressed byforming a structure in the non-pixel area, which may suppress theparticle cover layer from being excessively spread. The inventors havealso found that an evenness of the particle cover layer can be improvedas the excessive spread is suppressed.

In view of the above, an object of the present disclosure is to providean OLED device capable of suppressing an organic substance of a particlecover layer from being excessively spread, by forming a structure in anon-pixel area with a variety of configurations and materials.

Another object of the present disclosure is to provide an OLED device inwhich a multilayer structure for suppressing an organic substance frombeing excessively spread is formed in a non-pixel area, where a toplayer of the multilayer structure includes a plurality of subsidiarystructures, and the organic substance is dispersed via a storage spacedefined inside the subsidiary structures.

Yet another object of the present disclosure is to provide an OLEDdevice in which a plurality of stair-like dams for suppressing anorganic substance from being excessively spread is formed in a non-pixelarea, and the organic substance can be dispersed by the stair-like dams.

Yet another object of the present disclosure is to provide an OLEDdevice in which a metal structure for suppressing an organic substancefrom being excessively spread is formed in a non-pixel area, where themetal structure includes a plurality of subsidiary metal structures, andthe organic substance can be dispersed via a storage space definedbetween the plurality of subsidiary metal structures.

It should be noted that objects of the present disclosure are notlimited to the above-described object, and other objects of the presentdisclosure will be apparent to those skilled in the art from thefollowing descriptions.

According to an aspect of the present disclosure, an organiclight-emitting display (OLED) device may include a pixel area defined bya plurality of pixels on a flexible substrate; a non-pixel area aroundthe pixel area; a gate driver in the non-pixel area; a structure in thenon-pixel area configured to surround the pixel area; a firstencapsulation layer covering the plurality of pixels, the gate driverand the structure; and a particle cover layer covering the pixel areaand suppressed from being excessively spread by the structure.

The OLED device may further include a second encapsulation layercovering the first encapsulation layer and the particle cover layer.

The structure may include at least one of an organic material and aninorganic material, and the first encapsulation layer covering thestructure may resist penetration of moisture through the structure.

The structure may be a multilayer structure to suppress excessive spreadof the particle cover layer, and a top layer of the multilayer structuremay include a plurality of subsidiary structures, and the subsidiarystructures may be spaced apart from each other and include a storagespace to disperse the particle cover layer when the particle cover layeroverflows.

The multilayer structure may be made of the same material as materialsof at least two of a bank, a spacer, a planarizing layer and aninterlayer film disposed in the plurality of pixels.

The storage space may be configured to surround the pixel area.

The particle cover layer may be configured to planarize the pixel area,and a height of the particle cover layer near the structure may behigher than a height of the structure.

The structure may include a plurality of walls, and a wall disposedcloser to the inside among the plurality of walls may be lower than awall disposed closer to the outside among the plurality of walls.

The wall disposed closer to the inside may be a single layer and may bemade of the same material as a material of at least one of the bank, thespacer, the planarizing layer and the interlayer insulating filmdisposed in the plurality of pixels, and the wall disposed closer to theoutside may be a multilayer and may be made of the same materials asmaterials of at least two of the bank, the spacer, the planarizing layerand the interlayer insulating film disposed in the plurality of pixels.

The structure may include a plurality of dams, wherein a height of anouter dam may be higher than a height of an inner dam among theplurality of dams from the outside of the pixel area.

The OLED device may further include a second encapsulation layer; and aflexible encapsulation unit to seal the plurality of pixels and mayinclude the first encapsulation layer, the particle cover layer and thesecond encapsulation layer, and the particle cover layer may act as acompensation layer that planarizes the plurality of pixels and a heightof the particle cover layer gradually decreases from the outer peripheryof the plurality of pixels to the structure, and the particle coverlayer may be sealed by the first encapsulation layer and the secondencapsulation layer at the outer periphery of the plurality of pixels,and an area where the first encapsulation layer and the secondencapsulation layer come in contact with each other may be extendedbeyond the structure by a particular distance.

The structure may be a stair-like dam that may become higher towards theextended area.

The stair-like dam may include a plurality of subsidiary stair-like damsspaced apart from each other, and may include an interposed storagespace to disperse the particle cover layer when the particle cover layeroverflows.

The structure may be a metal structure made of a metal material.

The metal structure may further include a plurality of subsidiary metalstructures spaced apart from each other.

The metal structure may be made of one of silver (Ag), tin (Sn),aluminum (Al) and an indium tin oxide (ITO).

The OLED device may further include a second encapsulation layer; aflexible encapsulation unit disposed to cover the pixel area and thenon-pixel area, the flexible encapsulation unit may have the firstencapsulation layer, the second encapsulation layer, the structure andthe particle cover layer; and a barrier film may have apressure-sensitive adhesive layer and be attached on the flexibleencapsulation unit by the pressure-sensitive adhesive layer.

The barrier film may be attached on the second encapsulation layer ofthe flexible encapsulation unit.

The structure may have a particular height and may surround the particlecover layer in the non-pixel area, so that a portion of thepressure-sensitive adhesive layer may be pressed by the structure to beattached in the non-pixel area.

The structure may be a multilayer structure made of the same materialsas materials of at least two of a bank, a spacer, a planarizing layerand an interlayer film disposed in the plurality of pixels.

The multilayer structure may have a particular height that is capable ofsuppressing the excessively spread for increasing adhesion of thebarrier film.

A width in cross section of a top layer of the multilayer structure maybe narrower than a width in cross section of a bottom layer thereof.

Particulars of various example embodiments of the present disclosure areincluded in the detailed description and the accompanying drawings.

According to the embodiments of the present disclosure, a structure foreffectively suppressing a particle cover layer from being excessivelyspread is formed in a non-pixel area with a variety of configurationsand materials without requiring any additional process, so that theunwanted excessive spread problem of the particle cover layer in aflexible encapsulation unit can be improved.

In addition, according to the embodiments of the present disclosure, anevenness of a particle cover layer formed in a pixel area can beimproved.

Further, according to the embodiments of the present disclosure, anorganic substance can be disposed via a storage space by a structureincluding subsidiary structures, or a metal structure including aplurality of subsidiary metal structure or a plurality of subsidiarystair-like dams. As a result, defects in an OLED device can be reduced,and spots can be less perceived.

It should be noted that effects of the embodiments of the presentdisclosure are not limited to those described above and other effects ofthe embodiments of the present disclosure will be apparent to thoseskilled in the art from the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of theembodiments of the present disclosure will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a schematic plan view of an OLED device according to anexample embodiment of the present disclosure;

FIG. 2 is a schematic cross-sectional view of a sub-pixel of one of aplurality of pixels illustrated in FIG. 1;

FIG. 3 is a schematic cross-sectional view of the OLED device takenalong line III-III′ illustrated in FIG. 1;

FIG. 4 is an enlarged view of area X illustrated in FIG. 3;

FIG. 5A is a schematic enlarged view of an OLED device according toanother example embodiment of the present disclosure;

FIG. 5B is a schematic plan view for illustrating effects of a structurein an OLED device according to another example embodiment of the presentdisclosure;

FIG. 6A is a schematic enlarged view of an OLED device according to yetanother example embodiment of the present disclosure;

FIG. 6B is a schematic plan view for illustrating effects of a structurein an OLED device according to yet another example embodiment of thepresent disclosure;

FIG. 7A is a schematic enlarged view of a stair-like dam of an OLEDdevice according to yet another example embodiment of the presentdisclosure;

FIG. 7B is a schematic plan view for illustrating effects of thestair-like dam of an OLED device according to yet another exampleembodiment of the present disclosure;

FIG. 8A is a schematic enlarged view of a stair-like dam of an OLEDdevice according to yet another example embodiment of the presentdisclosure;

FIG. 8B is a schematic plan view for illustrating effects of thestair-like dam of an OLED device according to yet another exampleembodiment of the present disclosure;

FIG. 9 is a schematic enlarged view of a metal structure in an OLEDdevice according to yet another example embodiment of the presentdisclosure;

FIG. 10A is a schematic enlarged view of a metal structure in an OLEDdevice according to yet another example embodiment of the presentdisclosure; and

FIG. 10B is a schematic plan view for illustrating effects of the metalstructure in an OLED device according to yet another example embodimentof the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Advantages and features of the embodiments of the present disclosure andmethods to achieve them will become apparent from the descriptions ofexample embodiments herein below with reference to the accompanyingdrawings. However, the present disclosure is not limited to exampleembodiments disclosed herein but may be implemented in various differentways. The example embodiments are provided for making the disclosure ofthe present disclosure thorough and for fully conveying the scope of theembodiments of the present disclosure to those skilled in the art. It isto be noted that the scope of the embodiments of the present disclosureis defined only by the claims.

The figures, dimensions, ratios, angles, numbers of elements given inthe drawings are merely illustrative and are not limiting. Further, indescribing the present disclosure, descriptions on well-knowntechnologies may be omitted in order not to obscure the gist of thepresent disclosure. It is to be noticed that the terms “comprising,”“having,” “including” and so on, used in the description and claims,should not be interpreted as being restricted to the means listedthereafter unless specifically stated otherwise. Where an indefinite ordefinite article is used when referring to a singular noun, e.g., “a,”“an,” “the,” this includes a plural of that noun unless specificallystated otherwise.

In describing elements, they are interpreted as including error marginseven without explicit statements.

In describing positional relationship, such as “an element A on anelement B,” “an element A above an element B,” “an element A below anelement B,” and “an element A next to an element B,” another element Cmay be disposed between the elements A and B unless the term “directly”or “immediately” is explicitly used.

As used herein, a phrase “an element A on an element B” refers to thatthe element A may be disposed directly on the element B and/or theelement A may be disposed indirectly on the element B via anotherelement C.

The terms first, second, third and the like in the descriptions and inthe claims are used for distinguishing between similar elements and notnecessarily for describing a sequential or chronological order. Theseterms are used to merely distinguish one element from another.Accordingly, as used herein, a first element may be a second elementwithin the technical idea of the embodiments of the present disclosure.

Like reference numerals denote like elements throughout thedescriptions.

The width in the cross section of an element refers to the width in themiddle of the height of the cross section throughout the descriptions.

The angle of an element refers to an angle made by a plane and a slopedsurface in the middle of the height of the cross section throughout thedescriptions.

The drawings are not to scale and the relative dimensions of variouselements in the drawings are depicted schematically and not necessarilyto scale.

Features of various example embodiments of the present disclosure may becombined partially or totally. As will be clearly appreciated by thoseskilled in the art, technically various interactions and operations arepossible. Various example embodiments can be practiced individually orin combination.

FIG. 1 is a schematic plan view of an OLED device according to anexample embodiment of the present disclosure. FIG. 2 is a schematiccross-sectional view of a sub-pixel of one of a plurality of pixelsillustrated in FIG. 1. FIG. 3 is a schematic cross-sectional view of theOLED device taken along line III-III′ illustrated in FIG. 1. FIG. 4 is aschematic enlarged view of area X illustrated in FIG. 3.

An OLED device according to an example embodiment of the presentdisclosure includes a pixel area including a plurality of pixels, aflexible encapsulation unit protecting the pixel area, and a barrierfilm covering the flexible encapsulation unit. The flexibleencapsulation unit includes a first encapsulation layer formed in thepixel area and a non-pixel area, a structure formed in the non-pixelarea and surrounding the pixel area, a particle cover layer formedinside the structure, and a second encapsulation layer formed on thefirst encapsulation layer and the particle cover layer. The barrier filmis attached on the flexible encapsulation unit by a pressure-sensitiveadhesive layer.

Hereinafter, a top emission OLED device capable of suppressing aparticle cover layer from being excessively spread according to anexample embodiment of the present disclosure will be described withreference to FIGS. 1 to 4.

Referring to FIG. 1, an OLED device 100 includes: a plurality of pixels111 disposed on a flexible substrate 101; a gate driver 113 configuredto drive a plurality of gate lines 112; a data driver 115 configured toapply an image signal to a plurality of data lines 114; a common voltageline 116 disposed at the outer periphery of the gate driver 113 to applycommon voltage Vss to the plurality of pixels 111, and a flexibleencapsulation unit 130.

Each of the plurality of pixels 111 includes sub-pixels emitting lightof red, green and blue (RGB) colors. Each of the plurality of pixels 111may further include a sub-pixel emitting light of white color. Each ofthe sub-pixels may further include a color filter. The plurality ofpixels 111 is driven by thin-film transistors connected to the pluralityof gate lines 112 and the plurality of data lines 114 intersecting eachother. The area where the plurality of pixels 111 is disposed may bereferred to as a pixel area 110.

The data driver 115 generates a gate start pulse (GSP) for driving thegate driver 113 and a variety of clock signals. Further, the data driver115 converts a digital image signal received from an external sourceinto an analog image signal using a gamma voltage generated in a gammavoltage generator, and applies it to the plurality of pixels 111 via theplurality of data lines 114. The data driver 115 may be mounted on thesubstrate 101 by an anisotropic conductive film (ACF) applied onto aplurality of pads formed on the substrates 101. In addition, a flexibleprinted circuit (FPC), a cable, etc., may be mounted on anotherplurality of pads for receiving an image signal and a control signalfrom an external source by an ACF. The area where the pluralities ofpads are formed, on which the data driver 115, the FPC, etc., aremounted, may be referred to as a pad area 120. The ACF can be replacedwith a conductive adhesive or conductive paste and the embodiments ofthe present disclosure are not limited by the types of the conductiveadhesive means.

The gate driver 113 includes a plurality of shift registers. Each of theshift registers is connected to the respective gate lines 112. The gatedriver 113 receives a gate start pulse (GSP) and a variety of clocksignals from the data driver 115. As the shift registers in the gatedriver 113 shifts gate start pulses sequentially, each of the pluralityof pixels 111 connected to the respective gate lines 112 is activated.The non-pixel area corresponds to the area around the pixel area 110including the area where the gate driver 113 is formed, except the padarea 120.

The common voltage line 116 may be made of the same material as that ofthe gate lines 112 and/or the data lines 114 as a single layer or amultilayer. An insulating layer may be formed on the common voltage line116. The common voltage line 116 may supply a common voltage to a secondelectrode of each of the plurality of pixels 111. As illustrated in FIG.1, the common voltage line 116 is formed at the outer side of the pixelarea 110 and the gate driver 113 to surround them. For a top emissionOLED device, the second electrodes in the pixel area 110 have highelectric resistance. Accordingly, there is a problem in that theresistance of the second electrode increases as it becomes more distantfrom the common voltage line 116. In order to help relieve this problem,the common voltage line 116 is disposed to surround the pixel area 110.However, this is merely illustrative, and the common voltage line 116may be formed on at least one side of the pixel area 110. Toelectrically connect the second electrodes of the plurality of pixels111 to the common voltage line 116, the second electrodes may be formedon the gate driver 113 to be extended to a part of the gate driver 113.Further, the second electrodes may be connected to a connecting unitmade of the same material as that of the first electrodes formed on thegate driver 113. The connecting unit made of the same material as thatof the first electrodes may be formed over the gate driver 113 and maybe connected to the common voltage line 116 over the gate driver 113. Ifthere is an insulating layer between the connecting unit and the commonvoltage line 116, the connecting unit and the common voltage line 116may be connected to each other via a contact hole.

The flexible encapsulation unit 130 is formed to cover the pixel area110 and non-pixel area. In addition, the flexible encapsulation unit 130is formed not to cover the pad area 120. Specifically, the flexibleencapsulation unit 130 effectively protects the moisture permeation andalso has good electrical insulating property. Accordingly, in case theflexible encapsulation unit 130 covers the pad area 120, the pluralityof pads formed on the pad area 120 may be insulated. For this reason, itis desired that the flexible encapsulation unit 130 is not formed on thepad area 120.

The flexible encapsulation unit 130 includes a first encapsulation layer131, a second encapsulation layer 133, a structure 140 and a particlecover layer 132. In particular, in order to suppress the particle coverlayer 132 from being excessively spread, the structure 140 is formed inthe non-pixel area to surround the pixel area 110. In embodiments of thepresent disclosure, references to excessive spread refers to avoiding orreducing overflow of the particle cover layer 132 over the structure140. In other words, the structure 140 is arranged to contain or limitthe particle cover layer 132. The structure 140 surrounds the pixel area110 and the gate driver 113. The structure 140 partially overlaps thecommon voltage line 116. However, the structure 140 may be formed oninner or outer side of the common voltage line 116 rather than on thecommon voltage line 116. The structure 140 may also be formed on thegate driver 113 instead of the common voltage line 116. That is, thestructure 140 may be disposed anywhere in the non-pixel area as long asit surrounds the pixel area 110. The flexible encapsulation unit 130will be described in more detail with reference to FIG. 3. Inembodiments of the present disclosure, reference is made to thestructure 140 containing or limiting the particle cover layer 132. Inother embodiments of the present disclosure, use of the structure 140 isapplicable to instances of use for material, such as particle coverlayer.

Referring to FIG. 2, the OLED device 100 includes a substrate 101 madeof a flexible material, a thin-film transistor 220 disposed on thesubstrate 101, an organic light-emitting element 240 driven by thethin-film transistor 220, and a flexible encapsulation unit 130 sealingthe organic light-emitting element 240.

The substrate 101 may be a flexible film such as a polyimide-basedmaterial. In addition, a back plate for supporting the OLED device 100may be provided on the rear surface of the substrate 101 to suppress theOLED device 100 from being too flappy. Further, multiple buffer layersmade of silicon nitride SiN_(x) and silicon oxide SiO_(x) may bedisposed between the substrate 101 and the thin-film transistor 220,thereby protecting moisture and/or oxygen permeation into the substrate101.

The thin-film transistor 220 includes an active layer 221, a gateelectrode 222, a source electrode 223 and a drain electrode 224. Theactive layer 221 is covered by a gate insulating film 225 formed on thefront surface of the substrate 101. The gate electrode 222 is made ofthe same material as that of the gate line 112 and is formed on the gateinsulating film 225 over at least a part of the active layer 221. Thegate electrode 222 is covered by an interlayer insulating film 226formed on the front surface of the gate insulating film 225. Theinterlayer insulating film 226 may be formed in a multilayer structureof silicon nitride and silicon oxide. The thickness of the siliconnitride is between 0.2 μm and 0.4 μm, and the thickness of silicon oxideis, preferably, between 0.15 μm and 0.3 μm. More preferably, thethickness of silicon nitride is 0.3 μm, and the thickness of siliconoxide is 0.2 μm, and thus, the thickness of the interlayer insulatingfilm 226 is 0.5 μm. The source electrode 223 and the drain electrode 224are made of the same material as that of the data line 114 and areformed on the interlayer insulating film 226 spaced apart from eachother. The source electrode 223 is connected to one end of the activelayer 221 via a first contact hole 228 passing through the gateinsulating film 225 and the interlayer insulating film 226. The drainelectrode 224 is disposed over at least the other end of the activelayer 221 and is connected to the active layer 221 via a first contacthole 228 passing through the gate insulating film 225 and the interlayerinsulating film 226. The thin-film transistor 220 including the activelayer 221 is covered by a planarizing layer 227 formed on the frontsurface of the interlayer insulating film 226. Additionally, aninsulating layer made of silicon nitride for protecting the thin-filmtransistor 220 from contamination may be formed between the interlayerinsulating film 226 and the planarizing layer 227. The structure of thethin-film transistor 220 is not limited to that described above butvarious types of structure may be employed.

The organic light-emitting element 240 includes a first electrode 241, asecond electrode 243 facing the first electrode 241, and an organiclight-emitting layer 242 disposed between them. A light-emitting area ofthe organic light-emitting layer 242 may be defined by a bank 244.

The first electrode 241 is disposed on the planarizing layer 227 in thelight-emitting area of each of the pixels 111, and is connected to thedrain electrode 224 of the thin-film transistor 220 via a second contacthole 229 passing through the planarizing layer 227. The planarizinglayer 227 may be made of photo acryl having low dielectric permittivity.The thickness of the planarizing layer 227 is preferably between 2 μmand 3.5 μm, more preferably 2.3 μm By the planarizing layer 227 made ofthe material at the thickness, the first electrode 241 is less affectedby parasitic capacitance generated by the thin-film transistor 220, thegate line 112 or the data line 115. Further, the evenness of the firstelectrode can be improved.

The bank 244 is formed in a tapered shape on the planarizing layer 227in the non-emitting area of each of the pixels 111. The bank 244 isformed on the edge of the first electrode 241, overlapping at least apart thereof. The height of the bank 244 is preferably between 1 μm and2 μm, more preferably 1.3 μm. A spacer 245 is formed on the bank 244.The spacer 245 may be made of the same material as that of the bank 244.The bank 244 and the spacer 245 may be made of polyimide. The space 245serves to protect the organic light-emitting element 240 from beingdamaged by a fine metal mask (FMM) used in patterning the organiclight-emitting layer 242. The height of the spacer 245 is preferablybetween 1.5 μm and 2.5 μm, more preferably 2 μm. With the spacer 245having such height, the organic light-emitting element 240 can beprotected from being damaged by the mask. The spacer 245 may be formedwithout using a fine metal mask patterning.

In addition, since the heights of the planarizing layer 227, the bank244 and the spacer 245 are also related to the height of the structure140 described below, the height of the structure 140 may be determinedby taking the thickness of the particle cover layer 132 into account.

The organic light-emitting layer 242 is formed on the first electrode241. The second electrode 243 is formed such that it faces the firstelectrode 241 with the organic light-emitting layer 242 therebetween.The organic light-emitting layer 242 may be made of phosphor orfluorescent material, and may further include an electron transportlayer, a hole transport layer, a charge generation layer and etc.

The first electrode 241 may be made of a metal material having a highwork function. The first electrode 241 may be made of a reflectivematerial so that it has a reflective property or a reflective plate maybe additionally disposed under the first electrode 241. To the firstelectrode 241, an analog image signal is applied to display an image.

The second electrode 243 is made of a very thin, metal material having alower work function or a transparent conductive oxide (TCO). If thesecond electrode 243 is made of a metal material, it has a thicknessequal to or less than 400 Å. With such a thickness, the second electrode243 is a transflective (semitransparent) layer, and thus, the secondelectrode 243 is regarded as a substantially transparent layer. To thesecond electrode 243, the common voltage Vss is applied.

On the second electrode 243, a flexible encapsulation unit including afirst encapsulation layer, a particle cover layer, and a secondencapsulation layer 133 are formed. The flexible encapsulation unit 130will be described in more detail with reference to FIG. 3.

FIG. 3 illustrates a part of the OLED device 100, from the pixel area110 to an edge of the OLED device 100. Specifically, a substrate 101, apixel area 110 formed on the substrate 101, a gate driver 113 formed ona non-pixel area, a common voltage line 116 formed on the non-pixelarea, a flexible encapsulation unit 130 covering the pixel area 110 andthe non-pixel area, and a barrier film 350 are illustrated.

The gate driver 113 is composed of thin-film transistors which areformed with the thin-film transistors 220 which are included in theplurality of pixels 111 during the same manufacturing process.Therefore, the layered structure of the gate driver 113 will not bedescribed to avoid redundancy.

A structure 140 may be formed on the common voltage line 116. The heightof the structure 140 is increased by the thickness of the common voltageline 116. Detailed description of the elements described above withrespect to FIG. 1 will be omitted to avoid redundancy.

The flexible encapsulation unit 130 includes a first encapsulation layer131, a particle cover layer 132, a second encapsulation layer 133 and astructure 140. The first encapsulation layer 131 is configured to coverthe plurality of pixels 111, the gate driver 113, and the structure 140.The particle cover layer 132 covers the pixel area 110, while suppressedfrom being excessively spread by the structure 140. Thus, the particlecover layer 132 comes to abut the structure 140. The secondencapsulation layer 133 is configured to cover the first encapsulationlayer 131 and the particle cover layer 132. The structure 140 has aparticular height and surrounds the particle cover layer 132 in thenon-pixel area. The structure 140 has such a height that it suppressesthe particle cover layer 132 from being excessively spread, andincreases the adhesion between the barrier film 350 and the flexibleencapsulation unit 130.

The first encapsulation layer 131 is made of an inorganic substance. Thefirst encapsulation layer 131 may be formed with silicon nitride SiN_(x)or aluminum oxide Al_(y)O_(x) by using, but is not limited to, vacuumfilm deposition techniques such as a chemical vapor deposition (CVD), anatomic layer deposition (ALD), etc.

In case the encapsulation layer 131 is made of silicon nitride, thethickness of the first encapsulation layer 310 is preferably between5,000 Å and 15,000 Å, more preferably 10,000 Å. The water vaportransmission rate (WVTR) measurement was conducted on the firstencapsulation layer 131 having the thickness of 10,000 Å, and as aresult, the WVTR was measured to be 5.0×10⁻² g/m²/day.

In case the encapsulation layer 131 is made of aluminum oxide, thethickness of the first encapsulation layer 131 is preferably between 200Å and 1,500 Å, more preferably 500 Å. The WVTR measurement was conductedon the first encapsulation layer 131 having the thickness of 500 Å, andas a result, the WVTR was measured to be 1.3×10⁻³ g/m²/day.

The particle cover layer 132 is made of an organic substance. Theparticle cover layer 132 may be made of, but is not limited to, siliconoxycarbide (SiOC_(z)) or an acryl-based or epoxy-based resin. Aviscosity of the particle cover layer 132 for effectively coveringforeign matter is preferably between 500 centipoises (cps) and 30,000cps, and more preferably between 2,000 cps and 4,000 cps.

For example, in case the particle cover layer 132 is made of SiOC_(z),the particle cover layer 132 may be formed by a CVD process. SiOC_(z) isnormally an inorganic substance but can be regarded as an organicsubstance under a particular configuration. Specifically, theflowability of SiOC_(z) differs depending on the ratio between carbonatoms and silicon atoms (C/Si). For example, SiOC_(z) with lowerflowability acts like an inorganic substance, so that it covers foreignmatter less effectively. On the other hand, SiOC_(z) with higherflowability acts like an organic substance, so that it covers foreignmatter more effectively. The flowability was measured by varying theratio between the atoms. The result indicates that the flowabilitydecreases if the ratio between C/Si is equal to or higher thanapproximately 1.05, and the flowability increases if the ratio betweenC/Si is equal to or less than 1.0. Accordingly, foreign matter can beeasily covered if the ratio between C/Si is equal to or less than 1.0.Accordingly, the ratio between C/Si of SiOC_(z) of the particle coverlayer 132 is preferably 1.0 or less. In addition, by controlling thetemperature of deposition process to be 60° C. or less, the flowabilityis increased, so that the evenness of the particle cover layer 132improves, and thus, can cover foreign matter easily. Accordingly, thesecond encapsulation layer 133 can be formed on the even surface of theparticle cover layer 132.

The ratio between C/Si of SiOC_(z) may be controlled by adjusting theratio between oxygen O₂ and hexamethyldisiloxane (HMDSO) during a CVDprocess. The thickness of the particle cover layer 132 made of SiOC_(z)is preferably between 2 μm and 4 μm, more preferably 3 μm. Inparticular, in case the particle cover layer 132 is made of SiOC_(z),the flexible encapsulation unit 130 can be very thin, thus the OLEDdevice 100 can be thinner.

For example, in case the particle cover layer 132 is made of anacryl-based or an epoxy-based resin, the particle cover layer 132 may beformed by slit coating or screen printing process. In this case, as theepoxy-based resin, high-viscosity bisphenol-A based epoxy or lowviscosity bisphenol-F based epoxy may be applicable. The particle coverlayer 132 may further include additive agents. For example, a wettingagent for reducing the surface tension of the resin to improveuniformity of the resin, a leveling agent for improving the surfaceevenness of the resin, and a defoaming agent for removing foams in theresin may be added as the additive agents. The particle cover layer 132may further include an initiator. For example, an antimony-basedinitiator or an anhydride-based initiator may be applicable thatinitiates a chain reaction by heat to cure a liquid resin.

In particular, when the resin is thermally cured, it is important tocontrol the processing temperature to be below 110° C. In case the resinis thermally cured above 120° C., the already formed, organiclight-emitting layer 242 may be damaged. Accordingly, a resin that iscured below 110° C. is used.

Additionally, as the temperature of the resin increases, the viscosityof the liquid resin rapidly becomes low, and after a while, theviscosity rapidly becomes high as the resin is cured. However, while theviscosity of the resin is low, the flowability is too high. Therefore,excessive spread is especially highly likely to occur during this time.

The thickness of the particle cover layer 132 made of a resin may bebetween 15 μm and 25 μm, preferably 20 μm.

As illustrated in FIG. 3, the cross section of the particle cover layer132 has an even upper surface in the pixel area 110 and the thickness ofthe particle cover layer 132 becomes gradually thinner in the non-pixelarea. The portion of the particle cover layer 132 that becomes graduallythinner has a slope which may refract light, deteriorating the imagequality. Accordingly, the portion of the particle cover layer 132 thatbecomes gradually thinner is preferably located in the non-pixel area.

The particle cover layer 132 serves to cover foreign matter or particlesthat may be occurred during manufacturing processes. For example, theremay be a defect in the first encapsulation layer 131 due to a crackcaused by foreign matter or particles. The particle cover layer 132 maycover such an irregular surface or foreign matter, so that the topsurface of the particle cover layer 132 becomes even. That is, theparticle cover layer 132 compensates the foreign matters and planarizesthe pixel area 110 to the plurality of pixels 111. Consequently, theparticle cover layer 132 can be also referred as the compensation layer.Also, the height of the particle cover layer 132 is gradually decreasedfrom the outer periphery of the plurality of pixel 111 toward thestructure 140.

However, the particle cover layer 132 is not suitable for protecting theorganic light-emitting element 240 from moisture. Additionally, sincethe particle cover layer 132 has high flowability, it frequentlydeviates from the designed values.

The structure 140 according to an example embodiment of the presentdisclosure is formed in the non-pixel area of the OLED device 100. Thestructure 140 is spaced apart from the pixel area 110 and is spacedapart from the outermost periphery of the substrate 101. As illustratedin FIG. 3, the flow of the particle cover layer 132 is suppressed by thestructure 140.

Referring to FIG. 4, the structure 140 has a multilayer structure of afirst layer 141 and a second layer 142, for suppressing the particlecover layer 132 from being excessively spread. The first layer 141 andthe second layer 142 are formed while the bank 244 and the spacer 245are formed during the same process. That is, the structure 140 may beformed in a multilayer structure having a height between 2.5 μm and 4.5μm by a design alteration of a mask without undergoing any additionalprocess. In other words, the height of the structure 140 can be varieddepending on design of the bank 244 and the spacer 245. As describedabove, in case the heights of the bank 244 and the spacer 245 are 1.3 μmand 2 μm, respectively, the height of the multilayer structure 140 is3.3 μm. In particular, such a height of the structure 140 is optimizedfor the plurality of pixels 111. In embodiments of the presentdisclosure, the structure 140 may include at least one of an organicmaterial and an inorganic material, and the first encapsulation layer131 covering the structure 140 resists penetration of moisture throughthe structure 140.

The first encapsulation layer 131 is formed on the structure 140conforming to the shape of the structure 140. The slope θ of the wall ofthe first encapsulation layer 131 formed on the structure 140 is equalto the slope in the cross section of the first layer 141 and the secondlayer 142. The gradient of the slope of the bank 244 and the spacer 245in the cross section may range from 30° to 90° with respect to thesubstrate 101. The slope of the bank 244 may be equal to or differentfrom that of the spacer 245.

In case the particle cover layer 132 is made of SiOC_(z), the height ofthe structure 140 is similar to the height of the particle cover layer132, so that it is possible to effectively suppress the particle coverlayer 132 from being excessively spread. The particle cover layer 132 isformed such that conforming to the wall of the first encapsulation layer131 formed on the structure 140. That is, the particle cover layer 132has a corresponding shape according to the shape of the wall of thefirst encapsulation layer 131.

In addition, if the structure 140 is higher than the particle coverlayer 132 adjacent thereto, the structure 140 is capable of suppressingoverflow of the particle cover layer 132. Accordingly, the structure 140can be formed close to the pixel area 110 as much as possible. In thiscase, it is desirable to form the structure 140 spaced apart from thepixel area 110 by a distance L2 equal to or less than 1,000 μm.

In case the particle cover layer 132 is made of an acryl-based orepoxy-based resin, the height of the particle cover layer 132 may bebetween 15 μm and 25 μm. Accordingly, the height of the particle coverlayer 132 is higher than the height of the structure 140. As describedabove, the upper surface of the particle cover layer 132 is even withinthe pixel area 110 and the height of the particle cover layer 132 isgradually decreased within the non-pixel area. In this case, it ispreferably to form the particle cover layer 132 at a position where theheight of the particle cover layer 132 becomes lower to be equal to theheight of the structure 140, so that the structure 140 can effectivelysuppress the particle cover layer 132.

For example, if an epoxy-based resin used in an example embodiment ofthe present disclosure has the thickness of 20 μm and the viscosity of3,000 cps, it is desirable to form the structure 140 spaced apart fromthe pixel area 110 by 1,000 μm to 2,500 μm, which is regarded as anoptimal distance for this example. That is, at the particular distanceL2 which is regarded as the optimal distance, the structure 140 caneffectively suppress the particle cover layer 132 from overflowing.Therefore, it is important to keep the distance L2 for this example.However, the distance is not limited to the above example since theconfiguration varies depending on the height of the structure 140, thethickness and viscosity of the particle cover layer 132, and the areawhere it is applied.

In addition, the particle cover layer 132 may not flow over thestructure 140 even if the structure 140 is slightly lower than theparticle cover layer 132, as the particle cover layer 132 has a certainsurface tension.

The second encapsulation layer 133 is formed on the particle cover layer132 and the first encapsulation layer 131. The first encapsulation layer131 comes in contact with the second encapsulation layer 133 at theouter side of the structure 140. The length L1 of the area where thefirst encapsulation layer 131 comes in contact with the secondencapsulation layer 133 at the outer side of the structure 140 ispreferably 50 μm or greater. That is, the area where the firstencapsulation layer 131 comes in contact with the second encapsulationlayer 133 for sealing the particle cover layer 132 is extended from theouter periphery of the structure by a distance. In particular, as thefirst encapsulation layer 131 is configured to be in contact with thesecond encapsulation layer 133 at least 50 μm, the particle cover layer132 can be sealed by the first encapsulation layer 131 and the secondencapsulation layer 133 even if the particle cover layer 132 flows overthe structure 140. With this configuration, the particle cover layer 132is sealed by the first encapsulation layer 131 and the secondencapsulation layer 133, so that the direct path of moisture permeationvia the particle cover layer 132 is suppressed. In this case, the firstencapsulation layer 131 is larger than the second encapsulation layer133. Accordingly, the area of the second encapsulation layer 133 may besmaller than that of the first encapsulation layer 131. However, theembodiments of the present disclosure are not limited to the length L1or the area of the first encapsulation layer 131 and the area of thesecond encapsulation layer 133.

Further, as the second encapsulation layer 133 is formed on the evensurface, which is the upper surface of the particle cover layer 132, itis possible to significantly reduce cracks or seams due to foreignmatter and an irregular surface. Specifically, the second electrode 243is formed conforming to the bank 244 and the spacer 245. Accordingly,the second electrode 243 does not have an even surface. As the firstencapsulation layer 131 is formed conforming to the irregular surface ofthe second electrode 243, the first encapsulation layer 131 may havecracks due to the irregular surface. In contrast, the secondencapsulation layer 133 has an even surface. Accordingly, the secondencapsulation layer 133 may have fewer cracks than the firstencapsulation layer 131.

As illustrated in FIG. 3, after the second encapsulation layer 133 isformed, the barrier film 350 is attached on the second encapsulationlayer 133. By the barrier film 350, the OLED device 100 can furtherprotect the oxygen and moisture permeation. In particular, the processof attaching the barrier film 350 need not be carried out under strictvacuum conditions like a CVD process or an ALD process, but the barrierfilm 350 can be attached via a simple roll-to-roll laminating processwhile effectively protecting oxygen and moisture permeation by theflexible encapsulation unit 130. Accordingly, it is possible to avoidcumbersome repetitions of depositing organic insulating layers andinorganic insulating layers under vacuum conditions for suppressingdamages on the organic light-emitting element 240 by oxygen andmoisture, so that the process time can be significantly reduced andmanufacturing cost can be drastically saved. In addition, without thebarrier film adhered by a roll-to-roll process, more encapsulationlayers made of an inorganic substance may be required. Therefore, cracksare made easier in the flexible encapsulation unit as inorganicsubstance tends to be brittle by bending. However, by using the barrierfilm 350, the number of the layers of the inorganic substance depositedby a CVD can be reduced while effectively suppressing moisturepermeation. As a result, the good flexible encapsulation unit 130 can beimplemented. However, the embodiments of the present disclosure are notlimited by the barrier film.

The barrier film 350 includes a barrier film body 351 and apressure-sensitive adhesive layer 352. The barrier film body 351 may bemade of, but is not limited to, one of a copolyester thermoplasticelastomer (COP), a cycoolefin copolymer (COC) and a polycarbonate (PC).The barrier film 350 has to transmit image in the pixel area 110, andthus, preferably has optically isotropic properties in order to maintainthe quality of displayed images.

The thickness of the barrier film body 351 is preferably between 35 μmand 60 μm, more preferably 50 μm. With such a thickness, WVTR of thebarrier film 350 was measured to be 5×10⁻³ g/m²/day.

The capability of protecting the moisture permeation of the OLED device100 is determined based on the overall WVTR, taking into account WVTRsof the first encapsulation layer 131, the second encapsulation layer 133and the barrier film 350. Accordingly, in order to improve the WVTR ofthe OLED device 100, the relationship with the barrier film 350 is alsoimportant, as well as the first encapsulation layer 131 and the secondencapsulation layer 133.

Specifically, the thickness of the barrier film 350 may be determinedtaking into account the encapsulation performance of the firstencapsulation layer 131 and the second encapsulation layer 133. Forexample, in case the encapsulation performance of the firstencapsulation layer 131 and the second encapsulation layer 133 areimproved, the thinner the barrier film 350 can be applied.

The pressure-sensitive adhesive layer 352 is made of a transparent,two-sided adhesive film. In addition, the structure 140 is configured toprovide additional pressure to a corresponding portion of thepressure-sensitive adhesive layer 352 while the barrier film islaminated by a roll-to-roll process. As the height of the structureincreases, the additional pressure can be increased. Thepressure-sensitive adhesive layer 352 may be made of an insulativematerial such as olefin-based, acryl-based, and silicon-based materials.The pressure-sensitive adhesive layer 352 may have a thickness between 8μm and 50 μm. In particular, the pressure-sensitive adhesive layer 352may be made of a hydrophobic, olefin-based material that protects themoisture permeation. The pressure-sensitive adhesive layer 352 has thenature that its adhesion is increased if pressed at a constant pressure.If the pressure-sensitive adhesive layer 352 is made of a hydrophobic,olefin-based insulative material, the pressure-sensitive adhesive layer352 has a WVTR of 10 g/m²/day or less. In this manner, in addition thefirst encapsulation layer 131, the second encapsulation layer 133 andthe barrier film body 351, the oxygen and moisture permeation into thepixel area 110 can be further protected even by the pressure-sensitiveadhesive layer 352. As a result, the life span and reliability of theOLED device 100 can be improved.

An OLED device according to another example embodiment of the presentdisclosure includes a structure having a different configuration fromthat described above with respect to the above example embodiment.

Hereinafter, a top emission OLED device according to another exampleembodiment of the present disclosure will be described with reference toFIGS. 5A and 5B, which is capable of suppressing the particle coverlayer from being excessively spread.

FIG. 5A is a simplified enlarged view of an OLED device according toanother example embodiment of the present disclosure. FIG. 5B is aschematic plan view for illustrating effects of a structure in an OLEDdevice according to another example embodiment of the presentdisclosure.

Referring to FIG. 5A, a structure 540 in an OLED device 500 includes afirst layer 541 and a second layer 542. The first layer 541 is a singlelayer. The second layer 542 on the first layer 541 includes a pluralityof subsidiary structures 543 and 544. That is, the second layer 542located on the top of the multilayer structure 540 includes theplurality of subsidiary structures 543 and 544. A storage space 545 isdefined between the subsidiary structures 543 and 544 spaced apart fromeach other. The storage space 545 surrounds the pixel area 110. Thestorage space 545 may act as a channel or a canal, configured todisperse a particle cover layer 132 when the particle cover layer 132overflows the subsidiary structure 543. During the process of formingthe channel, a part of the first layer 541 may be etched to furtherdeepen the storage space 545.

The width in the cross section of the first layer 541 is preferablybetween 30 μm and 120 μm, more preferably between 40 μm and 50 μm. Thewidth in the cross section of the storage space 545 of the second layer542 is preferably between 10 μm and 30 μm, more preferably 20 μm. Thewidth in the cross section of the plurality of subsidiary structures 543and 544 of the second layer is 10 μm. That is, the width in the crosssection of the second layer 542 located on the top of the multilayerstructure 540 is narrower than that of the first layer 541 located onthe bottom thereof.

The widths in the cross sections of the plurality of subsidiarystructures 543 and 544 of the second layer 542 may differ from eachother. For example, the inner subsidiary structure 543 that is closer tothe outer periphery of the pixel area 110 may have a wider cross sectionthan the outer subsidiary structure 544 because the subsidiary structure543 has to bear the weight of the particle cover layer 132, like a damfor storing water.

By varying factors related to the storage space 545, the particle coverlayer 132 can be more effectively dispersed.

For example, by forming the plurality of subsidiary structures 543 and544 defining the storage space 545 closely to each other, capillaryaction can be more easily induced, so that the particle cover layer 132can be dispersed more quickly via the storage space 545. Capillaryaction is the ability of a liquid to flow in a narrow pipe without theassistance of, and in opposition to gravity.

For example, the viscosity of the particle cover layer 132 may belowered. As the viscosity of the particle cover layer 132 becomes low,the particle cover layer 132 can be dispersed more quickly via thestorage space 545.

For example, by adding a wetting agent to the particle cover layer 132in order to change its surface tension and in turn its wettability, theparticle cover layer 132 can be dispersed more quickly via the storagespace 545.

The plurality of subsidiary structures 543 and 544 is especiallyeffective when it is required to reduce the distance between thestructure 540 and the pixel area 110 in order to make a narrow bezel.

Referring to FIG. 5B, if the particle cover layer 132 flows over theinner subsidiary structure 543, the particle cover layer 132 isdispersed into two ways along the storage space 545. Accordingly, theparticle cover layer 132 is stored in the storage space 545 inside thesubsidiary structures 543 and 544, and thus, it is possible toeffectively suppress the particle cover layer 132 from flowing over theouter subsidiary structure 544 of the structure 540.

Preferably, the storage space 545 surrounds all four sides of the pixelarea of the OLED device 500. With this configuration, even if theparticle cover layer 132 flows over one of the four sides, the particlecover layer 132 can be effectively dispersed by the storage space 545formed along the four sides.

With the exception of the portions explained above, the OLED device 500according to another embodiment is identical to the OLED device 100 of aprevious embodiment, and thus, redundant features will not be describedfor the sake of brevity.

An OLED device according to yet another example embodiment of thepresent disclosure includes a structure with a different configurationfrom that described above with respect to the above example embodiments.

Hereinafter, a top emission OLED device according to another exampleembodiment of the present disclosure will be described with reference toFIGS. 6A and 6B, which is capable of suppressing the particle coverlayer from being excessively spread.

FIG. 6A is a schematic enlarged view of an OLED device according to yetanother example embodiment of the present disclosure. FIG. 6B is aschematic plan view for illustrating effects of a structure of an OLEDdevice according to yet another example embodiment of the presentdisclosure.

Referring to FIG. 6A, a structure 640 includes a plurality of subsidiarywalls 641, 642 and 643. The plurality of subsidiary walls 641, 642 and643 may act as dams. The first subsidiary wall 641 is a single layerstructure and is made of the same material as that of the bank 244 asillustrated in FIG. 2. The second subsidiary wall 642 is a double-layerstructure and is made of the same materials as that of the bank 244 andthe spacer 245 as illustrated in FIG. 2. The first subsidiary wall 641and the second subsidiary wall 642 are spaced apart from each other. Thethird subsidiary wall 643 is a triple-layer structure and is made of thesame materials as that of the bank 244, the spacer 245 and theplanarizing layer 227 as illustrated in FIG. 2. The second subsidiarywall 642 and the third subsidiary wall 643 are spaced apart from eachother. The wall 640 includes a first storage space 644 and a secondstorage space 645. The first subsidiary wall 641 is lower than thesecond subsidiary wall 642, and the second subsidiary wall 642 is lowerthan the third subsidiary wall 643. With this configuration, in case theparticle cover layer 132 overflows, the particle cover layer 132 can bedispersed firstly via the first storage space 644 between the firstsubsidiary wall 641 and the second subsidiary wall 642. Then, in casethe particle cover layer 132 overflows secondly, the particle coverlayer 132 can be dispersed via the second storage space 645 between thesecond subsidiary wall 642 and the third subsidiary wall 643.

That is, as the subsidiary walls 641, 642 and 643 become higher from theinside to the outside of the OLED device 600 with storage spaces 644 and645 formed between the subsidiary walls 641, 642 and 643, theoverflowing particle cover layer 132 can be dispersed more effectively.

The plurality of subsidiary walls 641, 642 and 643 is especiallyeffective when it is required to reduce the distance between thestructure 640 and the pixel area 110 in order to make a narrow bezel.

With the exception of the portions explained above, the OLED device 600according to another embodiment is identical to the OLED device 500 of aprevious embodiment, and thus, redundant features will not be describedfor the sake of brevity.

The OLED device according to the example embodiment of the presentdisclosure may be modified in a variety of ways.

In some embodiments, the number of subsidiary walls and layers of thesubsidiary walls may be designed in a variety of ways by selecting fromamong the bank 244, the spacer 245, the planarizing layer 227, theinterlayer insulating film 226 and/or the common voltage line 116 of theplurality of pixels 111.

In some embodiments, for the pixel area 110 having four sides, a portionof a structure formed on the first side may have three subsidiary wallsin parallel with the outer periphery of the pixel area 110 that arespaced apart from each other. The other portions of the structure formedon the second and third sides each may have two subsidiary walls thatare in parallel with the outer periphery of the pixel area 110 andspaced apart from each other, and the remaining portion of the structureformed on the fourth side may have one subsidiary wall that is inparallel with the outer periphery of the pixel area 110. That is,different numbers of subsidiary walls may be formed along the outerperiphery of the pixel area 110.

In some embodiments, the pixel area 110 may have walls spaced apart fromfour corners of the outer periphery, and shapes of the storage spaces atthe corners defined inside the walls may be a rounded shape, a curvedshape or diagonal shape, instead of storage spaces at a right angleshape. With such shapes, when the overflowing particle cover layer 132is dispersed from one side to another via a storage space, the flow ofthe particle cover layer can be facilitated at the corners. As a result,overflow of the particle cover layer at the corners can be suppressedand dispersion of the particle cover layer at the corners can beimproved.

In some embodiments, the pixel area 110 may have a circular or ovalshape. The structure formed around the pixel area 110 may be formed in acircular or oval shape, conforming to the pixel area 110.

FIG. 7A is a schematic enlarged view of a stair-like dam of an OLEDdevice according to yet another example embodiment of the presentdisclosure. FIG. 7B is a schematic plan view for illustrating effects ofthe stair-like dam of an OLED device according to yet another exampleembodiment of the present disclosure. With the exception of the portionsexplained above, the OLED device 700, according to the other embodimentas illustrated in FIGS. 7A and 7B, is identical to the OLED device 100of a previous embodiment as illustrated in FIG. 4, and thus, redundantfeatures will not be described for the sake of brevity.

Referring to FIGS. 7A and 7B, the height of the stair-like dam 740becomes higher toward the extended area where the first encapsulationlayer 131 contacts the second encapsulation layer 133. Specifically, thestair-like dam 740 has a multilayer structure including a first stair741 and a second stair 742. The first stair 741 and the second stair 742are formed during the processes of forming the bank 244 and the spacer245, respectively. That is, the stair-like dam 740 may be formed in amultilayer structure having a height between 2.5 μm and 4.5 μm by adesign alteration of a mask without undergoing any additional process.In other words, the height of the stair-like dam 740 can be varieddepending on design of the bank 244 and the spacer 245. As describedabove, in case the heights of the bank 244 and the spacer 245 are 1.3 μmand 2 μm, respectively, the height of the multi-layered, stair-like dam740 is 3.3 μm. In particular, such a height of the stair-like dam 740 isoptimized for the plurality of pixels 111. In addition, the stair-likedam 740 may be configured as three stairs by using the planarizing layer227. In this case, the overall thickness may be further increased by 3.5μm at most. That is, the maximum height of the stair-like dam 740 havingthree stairs may be up to 8 μm.

Referring to FIGS. 7A and 7B, the first inner wall 743 of the firststair 741 of the stair-like dam 740 may disperse the particle coverlayer 132 into two ways with respect to the first inner wall 743.Specifically, as illustrated in FIG. 7B, by the first inner wall 743,the particle cover layer 132 is dispersed into two ways indicated byarrows A1 with respect to the first inner wall 743. Accordingly, theparticle cover layer 132 is dispersed into the two ways with respect tothe first inner wall 743 before the particle cover layer 132 flows overthe first inner wall 743. Then, in case the particle cover layer 132flows over the first inner wall 743, it reaches the second stair 742 andis dispersed into two ways indicated by arrows A2 with respect to thesecond inner wall 744.

According to this configuration of the stair-like dam 740, when theparticle cover layer 132 overflows, it is effectively dispersed by thestairs sequentially.

The first encapsulation layer 131 is formed on the stair-like dam 740conforming to the shape of it. The slope θ of the wall of the firstencapsulation layer 131 formed on the stair-like dam 740 is equal to theslope in the cross section of the first stair 741 and the second stair742. The slope of the bank 244 and the spacer 245 in the cross sectionmay range from 30° to 90° with respect to the substrate 101. The slopeof the bank 244 may be equal to or different from that of the spacer245.

FIG. 8A is a schematic enlarged view of stair-like dams in an OLEDdevice according to yet another example embodiment of the presentdisclosure. FIG. 8B is a schematic plan view for illustrating effects ofthe stair-like dams in an OLED device according to yet another exampleembodiment of the present disclosure. The OLED device 800 as illustratedin FIGS. 8A and 8B includes stair-like dams different from thestair-like dam 740 as illustrated in FIGS. 7A and 7B.

Referring to FIG. 8A, the OLED device 800 includes a first subsidiarystair-like dam 840 a and a second subsidiary stair-like dam 840 b. Eachof the stair-like dams includes a first stair 841 a and 841 b and asecond stair 842 a and 842 b, respectively. The second stairs 842 a and842 b are formed on the first stair 841 a and 841 b, respectively. Thesecond stairs 842 a and 842 b are disposed more to the outside of thepixel area 110 at least by 5 μm than the first stairs 841 a and 841 b,respectively, in order to form the first stairs 841 a and 841 b. Astorage space 843 is defined between the first subsidiary stair-like dam840 a and the second subsidiary stair-like dam 840 b. The storage space843 may act as a channel configured to disperse the particle cover layer132 when the particle cover layer 132 overflows.

The width in the cross section of the first stairs 841 a and 841 b ispreferably between 30 μm and 100 μm, more preferably between 40 μm and50 μm. The widths in the cross section of the second stairs 842 a and842 b are preferably between 5 μm and 20 μm, more preferably between 10μm and 12 μm. The width of the storage space 843 is determined by thedistance between the first subsidiary stair-like dam 840 a and thesecond subsidiary stair-like dam 840 b. The distance is between 10 μmand 30 μm, more preferably 20 μm.

The width in cross section of the first stair 841 a of the firstsubsidiary stair-like dam 840 a may differ from that of the first stair841 b of the second subsidiary stair-like dam 840 b. For example, thefirst stair 841 a of the first subsidiary stair-like dam 840 a that iscloser to the pixel area 110 may have a wider cross section than thefirst stair 841 b of the second subsidiary stair-like dam 840 b becausethe first stair 841 a has to bear the weight of the particle cover layer132 more.

The width in cross section of the second stair 842 a of the firstsubsidiary stair-like dam 840 a may differ from that of the second stair842 b of the second subsidiary stair-like dam 840 b. For example, thesecond stair 842 a of the first subsidiary stair-like dam 840 a that iscloser to the pixel area 110 may have a wider cross section than thesecond stair 842 b of the second subsidiary stair-like dam 840 b becausethe second stair 842 a has to bear the weight of the particle coverlayer 132 more.

By varying factors related to the storage space 843, the particle coverlayer 132 can be more effectively dispersed.

For example, in case the distance between the subsidiary stair-like damsis reduced, the storage space 843 formed therebetween may promotecapillary action, so that the particle cover layer 132 can be dispersedmore quickly via the storage space 843.

For example, the viscosity of the particle cover layer 132 may belowered. As the viscosity of the particle cover layer 132 becomes low,the particle cover layer 132 can be dispersed more quickly via thestorage space 843.

For example, by adding a wetting agent to the particle cover layer 132in order to change its surface tension and in turn its wettability, theparticle cover layer 132 can be dispersed more quickly via the storagespace 843.

The plurality of subsidiary stair-like dams 840 a and 840 b isespecially effective when it is required to reduce the distance betweenthe subsidiary stair-like dams 840 a and 840 b and the pixel area 110 inorder to make a narrow bezel.

Referring to FIG. 5B, if the particle cover layer 132 flows over thefirst stair 841 a and the second stair 842 a of the first subsidiarystair-like dam 840 a sequentially, the particle cover layer 132 flowsinto the storage space 843 to be dispersed into two ways along thestorage space 843. Accordingly, the particle cover layer 132 is storedin the storage space 843, and it is possible to effectively suppress theparticle cover layer 132 from flowing over the second subsidiarystair-like dam 840 b.

Preferably, the storage space 843 surrounds all four sides of the pixelarea of the OLED device 800. With this configuration, even if theparticle cover layer 132 flows over one of the four sides, the particlecover layer 132 can be effectively dispersed by the storage space 843formed along the four sides.

With the exception of the portions explained above, the OLED device 800according to the other embodiment is identical to the OLED device 700 ofa previous embodiment, and thus, redundant features will not bedescribed for the sake of brevity.

FIG. 9 is a schematic enlarged view of a metal structure in an OLEDdevice according to yet another example embodiment of the presentdisclosure. The OLED device 900 illustrated in FIG. 9 is identical tothe OLED device 100 illustrated in FIG. 4 except that the structure 140in the OLED device 100 is replaced by a metal structure, and thus,redundant features will not be described for the sake of brevity).

The metal structure 940 is formed in the non-pixel area of the OLEDdevice 900. The metal structure 940 is spaced apart from the pixel area110 and is spaced apart from the outermost periphery of the substrate101. As illustrated in FIG. 9, the flow of the particle cover layer 132is blocked by the metal structure 940. Referring to FIG. 9, the metalstructure 940 may be formed via a screen printing process. Specifically,a metal paste is applied onto a mask of a metal mesh, and then asqueegee is moved. As a result, the metal structure 940 is appliedaround the particle cover layer 132. In the metal paste, an initiatormay be included that enables curing by heat or ultraviolet waves.

In particular, such a screen printing process has advantages in that itcan be carried out at a lower temperature than sputtering, which istypically used for metal deposition, and that it does not involve achemical process which may possibly damage the OLED device 240. Inaddition, when the metal structure is formed via such as a screenprinting process, it is possible to make the height of the metalstructure similar to the height of the particle cover layer 132.Specifically, the height of the metal structure 940 may be between 5 μmand 20 μm.

Further, the metal structure 940 may be produced via a dispensing nozzleprocess that is capable of applying a metal paste.

In addition, the metal structure 940 may be produced via an ink-jetcoating process that is capable of applying an ink containing a metal.

Further, the metal structure 940 may be produced via a rolling-printingprocess that is capable of applying a metal paste.

The metal structure 940 may be made of silver (Ag), tin (Sn), aluminum(Al), an indium tin oxide (ITO), etc.

The metal structure 940 may be formed on the common voltage line 116.Accordingly, the height of the metal structure 940 is increased as thethickness of the common voltage line 116 increases. Accordingly, thecommon voltage line 116 can be electrically connected to the metalstructure 940, and the same effect is obtained as if the thickness ofthe common voltage line 116 were increased. As a result, the capacity ofthe common voltage line 116 can be increased.

The first encapsulation layer 131 is formed on the metal structure 940conforming to the shape of the metal structure 940. The secondencapsulation layer 133 is formed on the particle cover layer 132 andthe first encapsulation layer 131. The first encapsulation layer 131comes in contact with the second encapsulation layer 133 at the outerside of the structure 940. With this configuration, the particle coverlayer 132 is sealed by the first encapsulation layer 131 and the secondencapsulation layer 133, so that the direct path of moisture permeationvia the particle cover layer 132 is suppressed.

FIG. 10A is a schematic enlarged view of a metal structure in an OLEDdevice according to yet another example embodiment of the presentdisclosure. FIG. 10B is a schematic plan view for illustrating effectsof the metal structure in an OLED device according to another exampleembodiment of the present disclosure. The OLED device 1000 illustratedin FIGS. 10A and 10B includes a different metal structure 1040 from theOLED device 900 illustrated in FIG. 9.

Referring to FIG. 10A, the structure 1040 in the OLED device 1000includes a first subsidiary metal structure 1041 and a second subsidiarymetal structure 1042. The first subsidiary metal structure 1041 and thesecond subsidiary metal structure 1042 are spaced apart from each other,and a storage space 1045 is defined therebetween. The storage space 1045may act as a channel.

The width in the cross section of the first subsidiary metal structure1041 and the second subsidiary metal structure 1042 is preferablybetween 10 μm and 100 μm, more preferably 20 μm. The width in the crosssection of the storage space 1045 is preferably between 10 μm and 30 μm,more preferably 20 μm.

The width in the cross section of the first subsidiary metal structure1041 may differ from that of the second subsidiary metal structure 1042.For example, the inner first subsidiary metal structure 1041 that iscloser to the outer periphery of the pixel area 110 may have a widercross section than the outer second subsidiary metal structure 1042because the first subsidiary metal structure 1041 has to bear the weightof the particle cover layer 132, like a dam for storing water.

By varying factors related to the storage space 1045, the particle coverlayer 132 can be more effectively dispersed.

For example, by forming the first and second subsidiary metal structures1041 and 1042 defining the storage space 1045 closely to each other,capillary action can be more easily induced, so that the particle coverlayer 132 can be dispersed more quickly via the storage space 1045. Inaddition, the viscosity of the particle cover layer 132 may be lowered,or a wetting agent may be added to the particle cover layer 132.

Referring to FIG. 10B, in case the particle cover layer 132 flows overthe inner first subsidiary metal structure 1041, the particle coverlayer 132 is dispersed into two ways along the storage space 1045.Accordingly, the particle cover layer 132 is contained in the storagespace 1045 inside the subsidiary metal structures 1041 and 1042, andthus, it is possible to effectively suppress the particle cover layer132 from flowing over the outer second subsidiary metal structure 1042of the metal structure 1040.

Preferably, the storage space 1045 surrounds all four sides of the pixelarea of the OLED device 1000. With this configuration, even if theparticle cover layer 132 flows over one of the four sides, the particlecover layer 132 can be effectively dispersed by the storage space 1045formed along the four sides.

Thus far, example embodiments of the present disclosure have beendescribed in detail with reference to the accompanying drawings.However, the present disclosure is not limited to the exampleembodiments, and modifications and variations can be made theretowithout departing from the technical idea of the present disclosure.Accordingly, the example embodiments described herein are merelyillustrative and are not intended to limit the scope of the presentdisclosure. The technical idea of the present disclosure is not limitedby the example embodiments. Therefore, it should be understood that theabove-described embodiments are not limiting but illustrative in allaspects. The scope of protection sought by the present disclosure isdefined by the appended claims and all equivalents thereof are construedto be within the true scope of the present disclosure.

What is claimed is:
 1. An apparatus comprising: a plurality of pixels on a substrate; a gate driver disposed outside of the plurality of pixels; a common voltage line disposed outside both of the gate driver and the plurality of pixels, the common voltage line having a first cross-sectional width; a dam structure configured to surround the plurality of pixels and disposed on at least a portion of the common voltage line, the dam structure having a second cross-sectional width narrower than the first cross-sectional width; a first inorganic encapsulation layer configured to cover the plurality of pixels, the gate driver, the common voltage line and the dam structure; a cover layer disposed on the first inorganic encapsulation layer and configured to be surrounded by the dam structure; and a second encapsulation layer disposed on the first encapsulation layer and the cover layer.
 2. The apparatus of claim 1, wherein the cover layer is completely sealed by the first inorganic encapsulation layer and the second inorganic encapsulation layer.
 3. The apparatus of claim 2, wherein the first inorganic encapsulation layer directly contacts the second inorganic encapsulation layer at an upper portion of the dam structure.
 4. The apparatus of claim 3, wherein the dam structure further comprises a plurality of walls.
 5. The apparatus of claim 4, wherein at least one wall among the plurality of walls is directly disposed on the common voltage line.
 6. The apparatus of claim 4, wherein the plurality of walls include a first wall and a second wall, and a height of the first wall closer to the plurality of pixels than the second wall is lower than a height of the second wall.
 7. The apparatus of claim 4, wherein a space formed between the plurality of walls contains an overflown portion of the cover layer, wherein the cover layer is a cured resin which has a flowability when the cover layer is not cured.
 8. The apparatus of claim 1, wherein the dam structure is formed of the same material as a material of at least one among a bank, a spacer, a planarizing layer and an interlayer insulating film disposed in the plurality of pixels.
 9. The apparatus of claim 1, wherein the plurality of pixels further comprises an organic light-emitting element including a first electrode and a second electrode, and the second electrode is electrically connected to the common voltage line.
 10. The apparatus of claim 1, wherein the plurality of pixels further comprises a thin-film transistor connected to a gate line and a data line, and the common voltage line is formed of the same material as that of the gate line or the data line.
 11. The apparatus of claim 10, wherein the common voltage is formed of a single layer.
 12. The apparatus of claim 10, wherein the common voltage is formed of multiple layers.
 13. A display device comprising: a substrate; a pixel area including a plurality of pixels on the substrate; a gate driver disposed outside of the pixel area; a common voltage line configured to surround the gate driver and the pixel area; a structure configured to surround the pixel area and the gate driver; a first inorganic encapsulation layer configured to cover the plurality of pixels, the gate driver, the common voltage line and the structure; a cover layer disposed on the first inorganic encapsulation layer and configured to be surrounded by the structure; and a second encapsulation layer disposed on the first encapsulation layer and the cover layer, wherein at least a portion of the structure is overlapped with the common voltage line.
 14. The display device of claim 13, wherein a length of an area where the first encapsulation layer comes in contact with the second encapsulation layer at the outer side of the structure is 50 μm or greater.
 15. The display device of claim 13, wherein a width of the common voltage line is wider than a width of the structure.
 16. The display device of claim 13, wherein the structure is spaced apart from the pixel area by a distance equal to or less than 1000 μm.
 17. The display device of claim 13, wherein the structure is formed of the same material as a material of at least one among a bank, a spacer, a planarizing layer and an interlayer insulating film disposed in the plurality of pixels.
 18. The display device of claim 13, wherein the structure further comprises a plurality of walls.
 19. The display device of claim 18, wherein the plurality of walls include a first wall and a second wall, and a height of the first wall closer to the plurality of pixels than the second wall is lower than a height of the second wall.
 20. The display device of claim 18, wherein a space formed between the plurality of walls contains an overflown portion of the cover layer. 